1Institute of Parasitic Diseases, Korea Association of Health Promotion, Seoul 07649, Korea2Department of Tropical Medicine and Parasitology, Seoul National University College of Medicine, Seoul 03080, Korea3Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea4Department of Parasitology and Parasite Research Center, Parasite Resource Bank, Chungbuk National University School of Medicine, Cheongju 28644, Korea5Department of Environmental Medical Biology, Institute of Tropical Medicine and Arthropods of Medical Importance Resource Bank, Yonsei University College of Medicine, Seoul 03722, Korea6Department of Microbiology and Immunology, Eulji University School of Medicine, Daejeon 34824, Korea7Department of Hygiene and Prevention, Ministry of Health, Vientiane, Lao PDR8Department of Parasitology, Korea University College of Medicine, Seoul 02841, Korea

Adult specimens of Echinochasmus caninus n. comb. (Verma, 1935) (Trematoda: Echinostomatidae) (syn. Episthmium caninum Yamaguti, 1958) were recovered from 11 riparian people who resided along the Mekong River in Khammouane Province, Lao PDR. In fecal examinations done by the Kato-Katz technique, the cases revealed eggs of Opisthorchis viverrini/minute intestinal flukes, hookworms, and in 2 cases echinostome eggs. To recover the adult helminths, praziquantel 30-40 mg/kg and pyrantel pamoate 10-15 mg/kg in a single dose were given and purged with magnesium salts. Various species of trematodes (including O. viverrini and Haplorchis spp.), cestodes, and nematodes were recovered from their diarrheic stools. Among the trematodes, small echinostome flukes (n=42; av. 3.8 specimens per case) of 0.7-1.2 mm in length are subjected in this study. They are morphologically characterized by having 24 collar spines interrupted dorsally and anterior extension of vitellaria from the cirrus sac or genital pore level to the posterior end of the body. Particularly based on this extensive distribution of vitellaria, the specific diagnosis was made as Echinochasmus caninus. The cases were co-infected with various other helminth parasites; thus, clinical manifestations specific for this echinostome infection were difficult to determine. The present paper describes for the first time human E. caninus infections in Lao PDR. Our cases marked the 4-14th human infections with this echinostome around the world following the 3 previous cases reported from Thailand.